This invention relates to the art of rolling mills and, more particularly, to a mechanism for vertically adjusting the lower roll of a multiple roll mill.
It is of course well known that the pass-line of a rolling mill is the path of movement of sheet metal through the mill between the working rolls thereof. It is likewise well known that the elevation of the pass-line with respect to the mill floor line must be maintained within reasonable limits regardless of the work and back-up roll diameters. In this respect, various devices such as strip guides, coolant sprays, bridle rolls, pass-line guide rolls, and the like are provided at fixed elevations with respect to the floor line on the entry and/or exit side of the mill. Accordingly, a number of procedures and mechanisms have been provided heretofore to enable vertical adjustment of the pass-line to maintain the latter within the limits established by such fixed equipment, or to maintain the lower roll of a multiple roll mill at an elevation within desired limits.
Many arrangements have been provided heretofore for achieving pass-line adjustment, including mechanisms operable between the lower back-up roll chocks and the mill housing to change the vertical positions of the chocks relative to the housing and thus the vertical position of the pass-line. Such mechanisms have included adjusting members interposed between the lower backup roll chocks and the mill housing and having upper surface portions associated with each of the chocks and varying in vertical height along the lengths of the surface portions. Thus, by changing the axial position of the adjusting member, the vertical positions of the chocks and thus the pass-line can be elevated or lowered. In certain arrangements heretofore provided, the upper surfaces of the adjusting member or members are vertically stepped to provide distinct increments of vertical adjustment of the chocks. The stepped surfaces of such adjusting members are directly engaged by the lower back-up roll chock assemblies and, accordingly, must be hardened or otherwise made wear resistant, which is procedurally expensive and time consuming from the standpoint of manufacture thereof. Moreover, in order to provide for small increments of vertical adjustment of the pass-line, the adjusting members are of a considerable length and, depending on the position of the adjustment member, they are exposed within the mill housing and/or adjacent the entry or exit side thereof. Accordingly, and especially during operation of the mill, lubricant, dirt, metal chips and the like can fall onto the exposed surfaces of the adjusting members causing undesirable wear and/or damage thereto and to surfaces of the chock assemblies engaging therewith. This problem results in increasing maintenance and down time for the mill in an effort to minimize such wear and damage. Still further, in connection with adjusting members having vertically stepped surface portions, arrangements heretofore employed to elevate and lower the backup roll chock assemblies to enable displacement of the adjusting member have been structurally complex and have been incorporated in the mill housing in association with the chocks, thus increasing production costs with respect to the mill and maintenance time and costs with respect to repair and/or displacement of the chock elevating mechanisms.